[PATCH] 2.5.5-dj2, modify arch/i386/Config.help for highpte options.

[PATCH] 2.5.5-dj2, modify arch/i386/Config.help for highpte options.

[Steven Cole]

This patch modifies the help text for the CONFIG_NOHIGHMEM option in
arch/i386/Config.help to explain the two new options; 
CONFIG_HIGHMEM4G_HIGHPTE and CONFIG_HIGHMEM64G_HIGHPTE.

Since this is a choice selection, the help text for the first option,
CONFIG_NOHIGHMEM is the only one which is visible using the current
configurators.

Here is a snippet from arch/i386/config.in both 2.5.5-dj2 and 2.5.6-pre1:

choice 'High Memory Support' \
        "off           CONFIG_NOHIGHMEM \
         4GB           CONFIG_HIGHMEM4G \
         4GB-highpte   CONFIG_HIGHMEM4G_HIGHPTE \
         64GB          CONFIG_HIGHMEM64G \
         64GB-highpte  CONFIG_HIGHMEM64G_HIGHPTE" off

If the notes for the highpte options are incorrect, feel free to provide 
a better explanation.

Steven

--- linux-2.5.5-dj2/arch/i386/Config.help.orig  Thu Feb 28 10:58:01 2002
+++ linux-2.5.5-dj2/arch/i386/Config.help       Thu Feb 28 11:52:43 2002
@@ -111,13 +111,21 @@
   possible.

   If the machine has between 1 and 4 Gigabytes physical RAM, then
-  answer "4GB" here.
+  answer "4GB" or "4GB-highpte" here.  The "4GB-highpte" option
+  will put user-space page table entries into high memory.
+
+  If the machine has more than 4 Gigabytes physical RAM, then
+  answer "64GB" or "64GB-highpte" here.  The "64GB-highpte" option
+  will put user-space page table entries into high memory.
+
+  Selecting either "64GB" or "64GB-highpte" turns Intel PAE
+  (Physical Address Extension) mode on.

-  If more than 4 Gigabytes is used then answer "64GB" here. This
-  selection turns Intel PAE (Physical Address Extension) mode on.
   PAE implements 3-level paging on IA32 processors. PAE is fully
   supported by Linux, PAE mode is implemented on all recent Intel
-  processors (Pentium Pro and better). NOTE: If you say "64GB" here,
+  processors (Pentium Pro and better).
+
+  NOTE: If you say "64GB" or "64GB-highpte" here,
   then the kernel will not boot on CPUs that don't support PAE!

   The actual amount of total physical memory will either be

Re: [PATCH] 2.5.5-dj2, modify arch/i386/Config.help for highpte options.

[Dave Jones]

On Thu, Feb 28, 2002 at 12:12:51PM -0700, Steven Cole wrote:
 > Here is a snippet from arch/i386/config.in both 2.5.5-dj2 and 2.5.6-pre1:
 > choice 'High Memory Support' \
 >         "off           CONFIG_NOHIGHMEM \
 >          4GB           CONFIG_HIGHMEM4G \
 >          4GB-highpte   CONFIG_HIGHMEM4G_HIGHPTE \
 >          64GB          CONFIG_HIGHMEM64G \
 >          64GB-highpte  CONFIG_HIGHMEM64G_HIGHPTE" off

 Would this not be better done using a "use highpte" bool in
 the !CONFIG_NOHIGHMEM case ? 
 
-- 
| Dave Jones.        http://www.codemonkey.org.uk
| SuSE Labs

Re: [PATCH] 2.5.5-dj2, modify arch/i386/Config.help for highpte options.

[Steven Cole]

On Thursday 28 February 2002 02:01 pm, Dave Jones wrote:
> On Thu, Feb 28, 2002 at 12:12:51PM -0700, Steven Cole wrote:
>  > Here is a snippet from arch/i386/config.in both 2.5.5-dj2 and
>  > 2.5.6-pre1: choice 'High Memory Support' \
>  >         "off           CONFIG_NOHIGHMEM \
>  >          4GB           CONFIG_HIGHMEM4G \
>  >          4GB-highpte   CONFIG_HIGHMEM4G_HIGHPTE \
>  >          64GB          CONFIG_HIGHMEM64G \
>  >          64GB-highpte  CONFIG_HIGHMEM64G_HIGHPTE" off
>
>  Would this not be better done using a "use highpte" bool in
>  the !CONFIG_NOHIGHMEM case ?

Maybe.  Here is a patch to arch/i386/config.in to try it that way.

Ingo, is this OK?

After the first patch, is another small patch to arch/i386/Config.help which
provides some explanation of CONFIG_HIGHPTE, which I hope is not
too inaccurate.  This supercedes the original change to arch/i386/Config.help.

Steven

--- linux-2.5.5-dj2/arch/i386/config.in.orig	Thu Feb 28 14:33:48 2002
+++ linux-2.5.5-dj2/arch/i386/config.in	Thu Feb 28 15:20:18 2002
@@ -161,25 +161,20 @@
 choice 'High Memory Support' \
 	"off           CONFIG_NOHIGHMEM \
 	 4GB           CONFIG_HIGHMEM4G \
-	 4GB-highpte   CONFIG_HIGHMEM4G_HIGHPTE \
-	 64GB          CONFIG_HIGHMEM64G \
-	 64GB-highpte  CONFIG_HIGHMEM64G_HIGHPTE" off
-if [ "$CONFIG_HIGHMEM4G" = "y" ]; then
-   define_bool CONFIG_HIGHMEM y
+	 64GB          CONFIG_HIGHMEM64G" off
+
+if [ "$CONFIG_HIGHMEM4G" = "y" -o "$CONFIG_HIGHMEM64G" = "y" ]; then
+   bool 'Use high memory pte support' CONFIG_HIGHPTE
 fi
-if [ "$CONFIG_HIGHMEM4G_HIGHPTE" = "y" ]; then
+
+if [ "$CONFIG_HIGHMEM4G" = "y" ]; then
    define_bool CONFIG_HIGHMEM y
-   define_bool CONFIG_HIGHPTE y
 fi
+
 if [ "$CONFIG_HIGHMEM64G" = "y" ]; then
    define_bool CONFIG_HIGHMEM y
    define_bool CONFIG_X86_PAE y
 fi
-if [ "$CONFIG_HIGHMEM64G_HIGHPTE" = "y" ]; then
-   define_bool CONFIG_HIGHMEM y
-   define_bool CONFIG_HIGHPTE y
-   define_bool CONFIG_X86_PAE y
-fi
 
 bool 'Math emulation' CONFIG_MATH_EMULATION
 bool 'MTRR (Memory Type Range Register) support' CONFIG_MTRR

--- linux-2.5.5-dj2/arch/i386/Config.help.orig  Thu Feb 28 10:58:01 2002
+++ linux-2.5.5-dj2/arch/i386/Config.help       Thu Feb 28 15:07:42 2002
@@ -128,6 +128,12 @@

   If unsure, say "off".

+CONFIG_HIGHPTE
+  The VM uses one page table entry for each page of physical memory.
+  For systems with a lot of RAM, this can be wasteful of precious
+  low memory.  Setting this option will put user-space page table
+  entries in high memory.
+
 CONFIG_HIGHMEM4G
   Select this if you have a 32-bit processor and between 1 and 4
   gigabytes of physical RAM.